java - 耗尽结果集错误

Question

我有这个代码可以从我的数据库中的帐户表中获取金额 但我收到此错误:耗尽结果集

  public int accountAmount(int custID){
        int amount=0;
        try{
            Class.forName("oracle.jdbc.driver.OracleDriver");
            Connection connection =
                    DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl" , "MYATM","myjava123");
            PreparedStatement statment =  connection.prepareStatement("select amount from Account where cust_id=?");
            statment.setInt(1,custID);
            ResultSet resultSet=statment.executeQuery();

            resultSet.next();

            amount= resultSet.getInt("amount");

            statment.close();
            connection.close();

        }
        catch (Exception ex){
            System.out.println(ex.getMessage());

        }


       return  amount;
    }

Answer 1

检查 ResultSet#next() 的返回类型;剧透 - 这是一个 boolean 值(如果为 false)表示您已经过了最后一行。所以，而不是这个

resultSet.next();
amount= resultSet.getInt("amount");

你需要这个!

if (resultSet.next()) {
  amount= resultSet.getInt("amount");
}